Metais tóxicos, tais como Ni, V, Zn, Cu, Cr, Mn, e metalóides, como As e Se e seus compostos estão associados normalmente com as partículas de pequeno diâmetro presentes nos aerossóis atmosféricos. Esse fato é importante, principalmente, quando se refere à saúde pública, pois esta é considerada a fração respirável das partículas que podem penetrar profundamente dentro dos pulmões e causar danos aos alvéolos. A concentração de metais traço na atmosfera, em geral, mostram níveis muito baixos, a determinação da composição elementar destas partículas requer o uso de técnicas analíticas apropriadas tais como: Indução de Partículas por Emissão de Raios X (PIXE), Análise por Ativação Neutrônica (AAN) e Espectrometria por Fluorescência de Raios X, dentre outras. O principal objetivo deste estudo foi a identificação das fontes de emissão de partículas grossas (MP10) e finas (MP2.5) presentes nos aerossóis atmosféricos da Região Metropolitana de Belo Horizonte. A Análise por Ativação Neutrônica pelo método-k0 (k0-AAN) combinada com a Fluorescência de Raios X por Energia Dispersiva (ED-XFR) foram usadas para medir a concentração dos elementos traço presentes em cada amostra. Altos níveis de concentração de particulados especialmente MP2.5, foram medidos durante o período de amostragem. Em geral, a qualidade do ar variou de Razoável a Inadequada. O modelo receptor usado para a identificação das principais fontes emissoras foi a Análise dos Componentes Principais (APC). Os resultados mostraram que os principais elementos presentes no material particulado inalável (MP2.5 e MP10) foram Ag, Al, As, Au, Ba, Br, Ca, Cl, Cr, Cu, Fe, K, Mn, Na, , S, Sb, Sc, Si, Ti, W e Zn. Os resultados para análise multivariada mostram claramente quatro fontes poluidoras, sendo estas: emissões veiculares; re-suspensão de poeira de solo/asfalto; aerossóis secundários associados com a emissão de SO2; e emissões industriais associadas com a queima de combustíveis fósseis. / Toxic metals, such as Ni, V, Zn, Cu, Cr, Mn and metalloids as As and Se and their compounds are mainly associated with the smaller diameter particulates present in the atmospheric aerosols. This fact is important, principally, when it concerns public health, because this is considered the breathable fraction of particles that can penetrate deeply into the lungs and cause damage to the alveoli. Once in the atmosphere the concentrations of trace metals, in general, show very low levels, thus the determination of the elementary composition of those particles requires the use of appropriate analytical techniques such as Particle Induced X-Ray Emission (PIXE), Neutron Activation Analysis (NAA) and X-Rays Fluorescence spectrometry (XRF), among others. The main objective of this study was the identification of the generating sources of gross (PM10) and fine (PM2.5) particles present in the atmospheric aerosols of the metropolitan region of Belo Horizonte. Neutron Activation Analyses by k0-method (k0-NAA) combined with Energy Dispersed by X-Ray Fluorescence was used to measurement of the concentration of trace elements present in each sample. High levels of particulate concentrations, especially PM2.5, were measured during the sampling period. In general, the air quality varied from Reasonable to Inadequate. The receptor model used to assist in the identification of the main emission sources was the Principal Components Analysis. The results showed that the main elements presents in particulate inhalable matter (PM2.5 and PM10) were Ag, Al, As, Au, Ba, Br, Ca, Cl, Cr, Cu, Fe, K, Mn, Na, , S, Sb, Sc, Si, Ti, W and Zn. The results for multi-variable analyses shown clearly four pollutant sources, these being: vehicular emissions; resuspended soil/asphalt powder; secondary aerosols associated with emission of SO2; and industrial emissions associated with fossil oil burning.

O resíduo estudado neste trabalho é originado do processo de obtenção de alumínio metálico, de grande interesse no Brasil pelo fato do país ser detentor de algumas das maiores reservas do mineral bauxita no mundo, utilizado como fonte de alumínio. Tendo como estratégia a geração de resíduo zero, colaborando para as tecnologias ambientalmente amigáveis, este trabalho estuda a incorporação de um resíduo resultante da recuperação de alumínio presente na escória gerada durante o processo de produção primária do alumínio metálico, por plasma térmico. Utilizando-se o diagrama de equilíbrio de fases do sistema Al2O3-CaO-SiO2, fez-se a adequação das composições visando a incorporação de resíduo no produto cerâmico sem alterar as características de processamento do material. A obtenção de vidros e de fritas vitrocerâmicas com o resíduo borra branca foi realizada fazendo-se a fusão das composições calculadas e, para os vitrocerâmicos, tratamento térmico posterior de devitrificação. Os produtos obtidos foram caracterizados utilizando-se técnicas de análise tais como difração de raios X (DRX), microscopia eletrônica de varredura (MEV) e espectroscopia do infravermelho (FTIR). Foi possível obter material vitrocerâmico com até 30% de resíduo de alumínio, após a fusão a 1300°C e devitrificação a 900°C. Em adição, o resíduo demonstrou ser um promissor material auxiliar na formação de fases cristalinas em baixos tempos de tratamento térmico. / This work studies the residue obtained from the process of aluminum metal extraction activities, a great interest process, because of Brazil own some of the biggest bauxite mineral reserves in all the world. As a useful choice for no residue generation, and a support for environmentally friendly technologies, this work studies the white dross residue (WDR), from the process of aluminum metal reduction by thermal plasma. The phase equilibrium diagram of Al2O3-Ca O-SiO2 system was used to calculate the compositions. The WDR were incorporated in a ceramic product without modifying its principal characteristics. The fusion and devitrification treatments were studied. XRD (X-ray diffractometry), SEM (scanning electron microscopy) and FTIR (transformed Fourier infrared) were used to investigate the glass and glassceramic samples. These techniques showed that is possible to get glassceramic with up to 30 mass% of WDR after molten at 1300 deg C and annealed at 900 deg C. In addition, the WDR showed to be a promising material in attainment of crystalline phases in less times of heat treatment for annealing.

O resíduo estudado neste trabalho é originado do processo de obtenção de alumínio metálico, de grande interesse no Brasil pelo fato do país ser detentor de algumas das maiores reservas do mineral bauxita no mundo, utilizado como fonte de alumínio. Tendo como estratégia a geração de resíduo zero, colaborando para as tecnologias ambientalmente amigáveis, este trabalho estuda a incorporação de um resíduo resultante da recuperação de alumínio presente na escória gerada durante o processo de produção primária do alumínio metálico, por plasma térmico. Utilizando-se o diagrama de equilíbrio de fases do sistema Al2O3-CaO-SiO2, fez-se a adequação das composições visando a incorporação de resíduo no produto cerâmico sem alterar as características de processamento do material. A obtenção de vidros e de fritas vitrocerâmicas com o resíduo borra branca foi realizada fazendo-se a fusão das composições calculadas e, para os vitrocerâmicos, tratamento térmico posterior de devitrificação. Os produtos obtidos foram caracterizados utilizando-se técnicas de análise tais como difração de raios X (DRX), microscopia eletrônica de varredura (MEV) e espectroscopia do infravermelho (FTIR). Foi possível obter material vitrocerâmico com até 30% de resíduo de alumínio, após a fusão a 1300°C e devitrificação a 900°C. Em adição, o resíduo demonstrou ser um promissor material auxiliar na formação de fases cristalinas em baixos tempos de tratamento térmico. / This work studies the residue obtained from the process of aluminum metal extraction activities, a great interest process, because of Brazil own some of the biggest bauxite mineral reserves in all the world. As a useful choice for no residue generation, and a support for environmentally friendly technologies, this work studies the white dross residue (WDR), from the process of aluminum metal reduction by thermal plasma. The phase equilibrium diagram of Al2O3-Ca O-SiO2 system was used to calculate the compositions. The WDR were incorporated in a ceramic product without modifying its principal characteristics. The fusion and devitrification treatments were studied. XRD (X-ray diffractometry), SEM (scanning electron microscopy) and FTIR (transformed Fourier infrared) were used to investigate the glass and glassceramic samples. These techniques showed that is possible to get glassceramic with up to 30 mass% of WDR after molten at 1300 deg C and annealed at 900 deg C. In addition, the WDR showed to be a promising material in attainment of crystalline phases in less times of heat treatment for annealing.

Ernst Alexander hat sich sowohl als experimentell als auch theoretisch äußerst fähiger Assistent von Georg von Hevesy im Institut für Physikalische Chemie der Universität Freiburg um die Entwicklung der Röntgenfluoreszenzanalyse verdient gemacht, habilitiert und wurde 1933 kurz nach seiner Ernennung zum Privatdozenten entlassen. Er ging an die Hebräische Universität Jerusalem, wo er das Arbeitsgebiet Experimentalphysik mit einer Institutswerkstatt aufgebaut, wesentliche Beiträge zur Röntgenstrukturanalyse geleistet und als Hochschullehrer fähige Wissenschaftler hervorgebracht hat. Während der kriegerischen Auseinandersetzungen stellte er Ersatzteile erst für die britische und dann für die israelitische Armee her. Ungeachtet seiner In Freiburg und in Jerusalem erbrachten Leistungen waren 1956 Institutsdirektor R. Mecke und der Dekan bei der Beurteilung seines Wiedergutmachungsantrages nicht bereit, ihm einen positiven Verlauf seiner akademischen Laufbahn zu bescheinigen, wenn er in Deutschland seine Arbeit hätte fortsetzen können. / Ernst Alexander was an assistant of George de Hevesy in the institute of physical chemistry of the university in Freiburg. He was a skillful experimenter with broad knowledge. He has done important contributions in the development of x-ray fluorescence analysis and has been qualified to give lectures at the university. In 1933 shortly after his appointment as lecturer he was dismissed. He went to the Hebrew University of Jerusalem, where he founded the laboratory of experimental physics with a workshop, where he dealt with x-ray structural analysis. During the war he produced spare parts for the British and later for the Israeli army. In 1956 he applied for reparation, but the head of the institute, R.Mecke and the dean did not accept that he would obtain a professorship if he must not leave Germany.

Studies have been carried out on specific ion-exchange (Dowex 50W-X8 and Dowex 1-X8) and chelation (Chelex-100) resins, in order to determine their physical and chemical characteristics, to understand and explain their limits of function and to optimise their use as substrates in trace metal and speciation measurement by EDXRF. Structural information was obtained by scanning electron microscopy and x-ray microanalysis showing a homogeneous distribution of functional groups and retained ions on both sectioned and whole resins. Particle size experiments performed on Dowex 50W-X8 (38 - 840 µm) showed that this parameter has no effect on the relationship between intensity of fluorescence and concentration or mass of resin. Inter-element effects were not observed in the analysis of multielemental specimens prepared on ion-exchange / chelation media by EDXRF. This indicates that the proposed method has a significant advantage when compared with other methodologies. A theoretical ‘model’, based on the formation of thin films on the surface of the resin beads, has been proposed in order to link and explain the effects observed in these experiments. The use of a batch retention system has shown distinct advantages over using columns in terms of linearity, accuracy, precision, rapidity and simplicity. Parameters such as pH and ionic strength of the solution, concentration of competing ions and volume of the sample have been proven to be critical. The maximum retention capacity has been determined as 3.2, 1.1 and 0.67 mEq/g for Dowex 50W-X8, Dowex 1-X8 and Chelex-100 respectively. The optimum mass of resin for XRF analysis was found to be 0.5 g, for all resins tested. The linear range covered 4 to 5 orders of magnitude. These findings show the potential of the investigated media to overcome instrumental and sample limitations. Based on the physico-chemical information found, methodologies for three different applications of the resins to EDXRF determinations have been developed and their analytical possibilities explored. The multi-elemental determination of metals in sewage sludge digests was achieved by retaining the metals on Dowex 50W-X8 at pH 2 and Chelex-100 at pH 4. Chelex-100 allows quantitative recoveries for Cu and Zn. A wider range of elements was determined on Dowex 50W-X8, although with poorer recoveries (60 - 90%). The limits of detection were 10 - 21 µg when Dowex 50W-X8 was used and 8 - 49 µg for Chelex-100. The method was validated by the analysis of a certified material. The determination of Kβ/Kα intensity ratios for Cr and Mn species and its potential as a tool for direct elemental speciation has also been studied. A difference in Kβ/Kα between the oxidation states of the analytes was only observed during the analysis of solutions of the metal species by EDXRF at the 98% level of confidence. Finally, the speciation and preconcentration of Cr(III) and Cr(VI) in waters has been performed by retention on Dowex 50W-X8 and Dowex 1-X8 followed by EDXRF determination. Efficient recoveries and preconcentration factors of up to 500 were achieved, leading to limits of detection of 30 µg/L for Cr(VI) and 40 µg/L for Cr(III). This method is simple, fast and inexpensive, allowing quantitative recoveries in the speciation of chromium in waste waters.

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